<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <script>
        'use strict'

        var map = new Map([['tom',100],['jack',90],['haha',80]]);
        for (let x of map){
            console.log(x)
        }

        var set = new Set([5,6,7])
        for (let x of set){
            console.log(x)
        }

    </script>

</head>
<body>

</body>
</html>